1. Field of the Invention
The present invention relates to a medical device for placing an embolic device, such as an embolic coil, at a predetermined site within a vessel, and more particularly relates to a catheter based deployment system for delivering an embolic coil. This device is particularly suited to transport an embolic device, through the tortious vasculature of the human brain and to the predetermined site within the vessel.
2. Description of the Prior Art
For many years, flexible catheters have been used to place various devices within the vasculature of the human body. Such devices include dilation balloons, radiopaque fluids, liquid medications, and various types of occlusion devices such as balloons and embolic coils. Examples of such catheter-based devices are disclosed in U.S. Pat. No. 5,108,407, entitled “Method and Apparatus for Placement of an Embolic Coil;” and U.S. Pat. No. 5,122,136, entitled “Endovascular Electrolytically Detachable Guidewire Tip for the Electroformation of Thrombus in Arteries, Veins, Aneurysms, Vascular Malformations and Arteriovenous Fistulas.” These patents disclose catheter-based devices designed to deliver embolic coils to a predetermined site within a vessel of the human body in order to treat aneurysms, or alternatively, to occlude a blood vessel at a particular location.
Coils which are placed in vessels may take the form of helically wound coils, or alternatively, may take the form of randomly wound coils, coils wound within coils or other such coil configurations. Examples of various coil configurations are disclosed in U.S. Pat. No. 5,334,210, entitled “Vascular Occlusion Assembly;” and U.S. Pat. No. 5,382,259, entitled, “Vasoocclusion Coil with Attached Tubular Woven or Braided Fibrous Covering.” Embolic coils are generally formed of a radiopaque metallic material, such as platinum, gold, tungsten, or an alloy of these metals. Often, several coils are placed at a given location to occlude the flow of blood through the vessel or aneurysm by promoting thrombus formation at the particular location.
Additionally, embolic coils have been placed within the distal end of a catheter, such that when the distal end of the catheter is properly positioned, the coil may then be pushed out of the end of the catheter with a pusher member to release the coil at the predetermined site within the vessel. This procedure for placement of the embolic coil is conducted under fluoroscopic visualization, such that the movement of a coil through the vasculature of the body may be monitored, and the coil may be placed in the desired location.
Another procedure involves the use of glue or solder to attach the coil to a guidewire, which is then placed within a flexible catheter for positioning the coil at a predetermined site within the vessel. Once the coil is at the predetermined site, the catheter holds the coil in position, and the guidewire is pulled proximally of the catheter to thereby detach the coil from the guidewire. Such a coil positioning system is disclosed in U.S. Pat. No. 5,263,964 entitled, “Coaxial Traction Detachment Apparatus and Method.”
Still another coil positioning procedure is that of having a catheter with a socket at the distal end, such that it retains a ball that is bonded to the proximal end of the coil. The ball, generally larger in diameter than the outside diameter of the coil, is placed in a socket within the lumen at the distal end of the catheter, and the catheter is then moved into a vessel in order to place the coil at a predetermined location. Once the site is reached, a pusher wire with a piston at the end thereof is pushed distally from the proximal end of the catheter to push the ball out of the socket, in order to release the coil at the predetermined site. Such a system is disclosed in U.S. Pat. No. 5,350,397, entitled, “Axially Detachable Embolic Coil Assembly.”
Another procedure for placing an embolic coil at a predetermined site within a vessel is that of using a heat releasable adhesive bond for retaining the coil at the distal end of the catheter. One such system uses laser energy transmitted through a fiber optic cable to apply heat to the adhesive bond in order to release the coil from the distal end of the catheter. Such a procedure is disclosed in aforementioned U.S. Pat. No. 5,108,407.
Still another coil deployment system incorporates an interlocking mechanism with the coil. The interlocking end of the embolic coil couples with a similar interlocking end on a pusher assembly. A control wire extends through the two interlocking ends to secure the coil to the pusher assembly. The pusher assembly and embolic coil are initially disposed within the lumen of a catheter. When the embolic coil is pushed out of the end of the catheter for placement, the control wire is retracted and the coil disengages from the pusher assembly. Such a deployment system is disclosed in U.S. Pat. No. 5,925,059, entitled, “Detachable Embolic Coil Assembly.”
Yet another coil deployment system incorporates an embolic device detachably mounted on the distal portion of a pusher member and held in place with a connector thread or fiber. The fiber passes through a cutter member that may be activated to cut the connector fiber. Once the connector fiber is cut, the embolic device is released. Such a deployment system is disclosed in Published U.S. Patent Application No. 2002/0165569, and entitled, “Intravascular Device Deployment Mechanism Incorporating Mechanical Detachment.”
Still another coil deployment system incorporates an embolic device with a stretch resistant member therethrough. The distal end of the stretch resistant member is attached to the embolic coil, and the proximal end of the stretch resistant member is detachably mounted on an elongated pusher member to allow for placement and release of the coil within a vessel. The stretch resistant member is detachably mounted on the pusher member through various means, such as adhesive or by a connector fiber adhered to or tied onto the pusher member and is detachable by the application of heat. Such a deployment system is disclosed in Published U.S. Patent Application No. 2004/0034363, entitled, “Stretch Resistant Therapeutic Device.”
Still another coil deployment system incorporates a platinum wire and or tip that is inserted into a vascular cavity. The tip may be elongated and flexible, folded upon itself several times, or may have a branched configuration. The tip may be separated from the wire mechanically or via electrolytic separation. Such a system is disclosed in U.S. Pat. Nos. 5,540,680; 5,895,385; 5,925,037; and 5,976,126, all entitled, “Endovascular Electrolytically Detachable Wire and Tip for the Formation of Thrombus in Arteries, Veins, Aneurysms, Vascular Malformations, and Arteriovenous Fistulas.”
Still another coil deployment system incorporates a pusher member, having a stiff wavy-shaped wire end segment, coupled to an embolic coil and placed within the lumen of the catheter. The coil is advanced through the catheter until it reaches the predetermined site within the vessel, at which time the pusher member is retracted and the embolic coil is released. Such a system is disclosed in U.S. Pat. No. 6,203,547, entitled, “Vaso-occlusion Apparatus Having a Manipulable Mechanical Detachment Joint and a Method for Using the Apparatus.”
Still another embolic device deployment system includes an elongated flexible pusher member slidably disposed within a lumen of a catheter. An embolic device is retained at the end of the pusher member with a detachment filament. When the embolic device is advanced to the predetermined site within the vessel, the detachment filament is withdrawn releasing the embolic device. Such a system is disclosed in U.S. patent application Ser. No. 11/145,350 filed on Jun. 3, 2005, entitled, “Embolic Device Deployment System with Filament Release.”